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网络请求–Retrofit2使用方法

 3 years ago
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Retrofit是Square开发的网络请求库, 简化了网络请求的使用, 这个库太知名了, 好处我就不多说了. 让我们看看如何使用吧?

注意: Retrofit2的beta3版本, 使用Okhttp3, Interceptor使用方式发生改变.

Retrofit

(1) Retrofit2(beta3)的请求方式.

(2) Okhttp3的Interceptor.

(3) Okhttp3的Deserializer.

(4) Retrofit2使用Gson转换器(Converter)和RxJava适配器(Adapter).

Github下载地址

1. 基本请求

使用接口, 区分Get和Post方法.

/**
* 网络请求
* <p>
* Created by wangchenlong on 16/1/21.
*/
public interface MarvelService {
String END_POINT = "http://gateway.marvel.com/";
String PARAM_API_KEY = "apikey";
String PARAM_HASH = "hash";
String PARAM_TIMESTAMP = "ts";
@GET("/v1/public/characters")
Observable<List<AvengersCharacter>> getCharacters(@Query("offset") int offset);
}

使用Retrofit类创建接口服务, 指定Gson为转换器, RxJava为适配器.

public class RestDataSource implements Repository {
private final MarvelService mMarvelService;
@Inject
public RestDataSource() {
// Log信息
HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor();
loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BASIC);
// 公私密匙
MarvelSigningInterceptor signingInterceptor = new MarvelSigningInterceptor(
BuildConfig.MARVEL_PUBLIC_KEY, BuildConfig.MARVEL_PRIVATE_KEY);
// OkHttp3.0的使用方式
OkHttpClient client = new OkHttpClient.Builder()
.addInterceptor(signingInterceptor)
.addInterceptor(loggingInterceptor)
.build();
// 选择人物信息
Gson customGsonInstance = new GsonBuilder()
.registerTypeAdapter(new TypeToken<List<AvengersCharacter>>() {
}.getType(),
new MarvelResultsDeserializer<AvengersCharacter>())
.create();
// 适配器
Retrofit marvelApiAdapter = new Retrofit.Builder()
.baseUrl(MarvelService.END_POINT)
.addConverterFactory(GsonConverterFactory.create(customGsonInstance))
.addCallAdapterFactory(RxJavaCallAdapterFactory.create())
.client(client)
.build();
// 服务
mMarvelService = marvelApiAdapter.create(MarvelService.class);
}
// 返回人物信息
@Override
public Observable<List<AvengersCharacter>> getCharacters(int currentOffset) {
return mMarvelService.getCharacters(currentOffset);
}
}

2. Interceptor

Interceptor是拦截器, 在发送之前, 添加一些参数, 或者获取一些信息.

如MarvelSigningInterceptor是添加参数, loggingInterceptor是打印参数.

/**
* 添加Key和密码
* <p>
* Created by wangchenlong on 16/1/21.
*/
public class MarvelSigningInterceptor implements Interceptor {
private final String mApiKey;
private final String mApiSecret;
public MarvelSigningInterceptor(String apiKey, String apiSecret) {
mApiKey = apiKey;
mApiSecret = apiSecret;
}
@Override public Response intercept(Interceptor.Chain chain) throws IOException {
String marvelHash = MarvelApiUtils.generateMarvelHash(mApiKey, mApiSecret);
Request oldRequest = chain.request();
// 添加新的参数
HttpUrl.Builder authorizedUrlBuilder = oldRequest.url()
.newBuilder()
.scheme(oldRequest.url().scheme())
.host(oldRequest.url().host())
.addQueryParameter(MarvelService.PARAM_API_KEY, mApiKey)
.addQueryParameter(MarvelService.PARAM_TIMESTAMP, MarvelApiUtils.getUnixTimeStamp())
.addQueryParameter(MarvelService.PARAM_HASH, marvelHash);
// 新的请求
Request newRequest = oldRequest.newBuilder()
.method(oldRequest.method(), oldRequest.body())
.url(authorizedUrlBuilder.build())
.build();
return chain.proceed(newRequest);
}
}

addQueryParameter添加网络参数.

Okhttp3使用了装饰者模式, 使用Builder添加Interceptor.

// OkHttp3.0的使用方式
OkHttpClient client = new OkHttpClient.Builder()
.addInterceptor(signingInterceptor)
.addInterceptor(loggingInterceptor)
.build();

3. Deserializer

Deserializer是反序列化, Gson使用, 去除不使用的参数.

public class MarvelResultsDeserializer<T> implements JsonDeserializer<List<T>> {
@Override
public List<T> deserialize(JsonElement je, Type typeOfT,
JsonDeserializationContext context) throws JsonParseException {
// 转换Json的数据, 获取内部有用的信息
JsonElement results = je.getAsJsonObject().get("data")
.getAsJsonObject().get("results");
return new Gson().fromJson(results, typeOfT);
}
}

Gson使用Deserializer, 过滤不用的参数.

// 选择人物信息
Gson customGsonInstance = new GsonBuilder()
.registerTypeAdapter(new TypeToken<List<AvengersCharacter>>() {
}.getType(),
new MarvelResultsDeserializer<AvengersCharacter>())
.create();

4. 获取数据

Rx选择执行线程和返回线程.

private void loadData() {
mCharactersSubscription = mRepository.getCharacters(0)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(avengersCharacters -> {
mMainView.setListData(avengersCharacters);
});
}

Rxjava+Dagger+Retrofit, 三个编程库, 都已经写完了, 基本都是在一起使用. 文章里面都含有独立Demo, 大家可以配合使用, 感谢Square给我们带来, 的优雅代码.

OK, that’s all! Enjoy it.

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